Automated mechanical handling systems (AMHSs) are widely used during integrated circuit fabrication to organize, handle, and track supplied wafers in a fabrication facility to use in fabrication of integrated circuits in the most efficient manner possible. AMHSs generally employ carrier storage positions, e.g., storage positions in a stocker or zero footprint storage bins. The carrier storage positions are adapted to receive a wafer carrier, such as a front opening shipping box (FOSB). The AMHSs also generally include a container transporter that is adapted to move the FOSBs into and out of the carrier storage positions. During handling, FOSBs that include the supplied wafers are removed from the carrier storage positions and unwrapped, followed by placing the supplied wafers and an empty front opening unified pod (FOUP) on a sorter. The FOUP allows the supplied wafers to be accessed during automated integrated circuit fabrication. The supplied wafers are transferred to the empty FOUP on the sorter. The FOUP is then generally returned to the carrier storage position, where the FOUP remains until the supplied wafers are needed.
Queue times during automated integrated circuit fabrication have a significant impact on integrated circuit quality due to environmental impact on materials that are used to fabricate the integrated circuits. In particular, prolonged exposure to moisture or other airborne environmental contaminants such as organic compounds and ions can lead to corrosion and/or crystallization on the wafers, thereby resulting in out-of-specification integrated circuits that must be discarded or reworked. To avoid excessive queue times, fabrication facilities often employ production holds at various stages in the fabrication to ensure that queue times are not exceeded that would otherwise result in rework and scrap of fabricated integrated circuits. Wafer Environment Control (WEC) solutions are another option that has been considered to prevent contamination of the supplied wafers from moisture and organic compounds that may be present in the ambient atmosphere surrounding the carrier storage positions while the supplied wafers are stored. The WEC solutions, in principle, provide a chemically inert environment surrounding the supplied wafers while the supplied wafers await use during integrated circuit fabrication, thereby rendering long queue times immaterial to product quality. WEC solutions have been developed whereby wafer carriers are provided with in inlet port and an outlet port. When placed in the carrier storage positions, an inert gas such as nitrogen is introduced into the wafer carrier, and the inert gas may be drawn through the wafer carrier by applying a vacuum to the outlet port. Alternatively, gases may simply escape from the outlet port due to a pressure differential created by the flow of inert gas into the wafer carrier. However, if a malfunction occurs in gas flow through the inlet port and/or vacuum applied to the outlet port in the carrier storage position that contains the wafer carrier, effectiveness of the WEC may be compromised leading to corrosion and/or crystallization on the wafers and resulting in a missed processing event.
Accordingly, it is desirable to provide AMHSs, system computers programmed for use in the AMHSs, and methods of handling a wafer carrier having an inlet port and an outlet port that enable minimization of missed processing events due to malfunction in gas flow through the inlet port in carrier storage positions. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.